Answers

sorry i dissagree bamboo . i believe with carefull pruning from thestart you could keep most trees managable just bye cutting the right bits out . id at least try cutting the growing tip out and keep it that hight or as bamboo sais cutting the lower branches etc which i prefer .there stunning trees . ive got 2 in my littly front garden and im going to do as you say bamboo . then they wont realy take up much room lol . i know my front gardens totaly against all the rule books ie overcrowding but the soil is naturaly brilliant here . i actualy fertize the plants with pond pellets and water them from the nuetriant rich pond water and touch wood no problemo lol x .

Yes, that's fine, as I said, but what isn't fine is removing the top. Its a large tree, and trying to keep it smaller by cutting the main trunk at the top on the poor thing won't do it any good at all. Ultimate height for this one is 66 feet, and it has apical domination in the main trunk.

We remove the lower branches from ours - ouch! You don't want to brush pass those when mowing! We've not tried to restrict ours - we'll just enjoy it until it outgrows its space before it has to go ..... quite slow growing, arent they, so maybe I'll be six foot under before the tree.

I love Monkey Puzzle trees and have often seen ones where owners have removed the lower branches for safety/just to cut the grass. They look fine like that - as nature often self-prunes the lower branches as they grow.
What looks terrible is when someone chops off the top!! They have a different growing shape to most other conifers and although I "candle" some of my pines to reduce the length of the new branches - nothing like that works successfully on a Monkey Puzzle.
I think that if you take the top off - it will only be a matter of time until you realise how bad it looks and take it out anyway. So two lots of work instead of one. (One final possibility - I have seen ones where the leader was damaged and a branch then curved upward to make a new leader - which also looked awful.)